Chromatic dispersion measurement based on a high-Q optoelectronic oscillator incorporating cascaded FIR and IIR filters

Abstract

An approach for chromatic dispersion measurement is proposed and experimentally demonstrated based on an optoelectronic oscillator (OEO) incorporating a single bandpass microwave photonic filter (MPF), which is implemented by cascading a finite impulse response (FIR) MPF and an infinite impulse response (IIR) MPF jointly. The key concept of the proposed design is mapping the chromatic dispersion of a device under test (DUT) to the oscillating frequency of the OEO by embedding the DUT into the OEO loop. The oscillating frequency is mainly determined by the central frequency of the MPF, which depends on the length difference of the two arms of the Mach-Zehnder interferometer (MZI) and the chromatic dispersion value of the fiber cooperatively. The bandwidth of the MPF is further narrowed by an IIR filter based on a recirculating fiber loop for stabilizing OEO oscillation. The chromatic dispersion of fibers with lengths ranging from 20 km to 100 km are measured in the experiment.